1. Field of the Invention
A pinch valve construction for modulating and curtailing the flow of a fluid.
2. Description of the Prior Art
Pinch valves basically consist of a flexible resilient cylindrical elastomeric sleeve or the like which is interposed in a continuous conduit, duct, pipe, or tube, together with means to constrict the sleeve so as to curtail or control the flow of fluid through the conduit or the like. In most instances, the sleeve is concentrically oriented within an outer rigid valve housing, and means are provided to impress a fluid under pressure between the sleeve and the housing so that the sleeve is squeezed inwards and deformed or collapsed to provide a smaller fluid flow passage. In other instances, mechanical means are provided to pinch the sleeve to accomplish the same result. One problem encountered with pinch valves of the prior art is a tendency of the joints between the sleeve and/or the valve housing, and the continuous lengths of conduit or the like, to ultimately leak due to distortion of the sleeve and repeated flexing of the same.
Normally, a pinch valve sleeve is made from pure gum rubber, neoprene, BUNA, butyl, hypalon, urethane, viton, EPT (nordel), silicone and food grade rubber.
Pinch valve constructions, as generally described herein, have been used in a wide variety of situations. More specifically, pinch valve constructions as described herein have been used in controlling the flow of, by way of example, solids in suspension (either in slurry or air-conveyed form), especially abrasive materials such as metallic ores, asbestos fibers, sand, coal, sugar, wood chips or pulps, paper stock, plastic pellets, raw sewage, talc, cement, fly ash, and various chemicals and foodstuffs.
Among the prior art relating to pinch valve constructions may be mentioned U.S. Pat. Nos. 4,125,125; 3,838,704; 3,483,892; 3,445,085; 3,441,245; 3,396,448; 3,371,677; 3,272,470 and 3,159,373; U.S. Pat. Application Ser. No. 830,453 filed Sept. 6, 1977 now U.S. Pat. No. 4,172,580; German Pat. No. 1,038,850; British Pat. No. 639,646 and Italian Pat. No. 535,034.